Mushroom fell off

[likwid]

Hey guys,

I purchased a small piece of live rock with a couple mushrooms attached to it. They are both fairly big, and have opened up very nicely. I woke up one morning and one of the mushrooms detached from the rock and is laying on the sand bed. It is still alive, and opens up nicely when my daylights are one. What does this mean, and how can I attach it back to a rock? Sorry for the newb questions, this is my first coral purchase.